#
# RFC822 Email Address Regex
# --------------------------
#
# Originally written by Cal Henderson
# c.f. http://iamcal.com/publish/articles/php/parsing_email/
#
# Translated to Ruby by Tim Fletcher, with changes suggested by Dan Kubb and
# Simon Wex.
#
# Licensed under a Creative Commons Attribution-ShareAlike 2.5 License
# http://creativecommons.org/licenses/by-sa/2.5/
#
RFC822 = begin
  qtext = '[^\\x0d\\x22\\x5c\\x80-\\xff]'
  dtext = '[^\\x0d\\x5b-\\x5d\\x80-\\xff]'
  atom = '[^\\x00-\\x20\\x22\\x28\\x29\\x2c\\x2e\\x3a-' +
    '\\x3c\\x3e\\x40\\x5b-\\x5d\\x7f-\\xff]+'
  quoted_pair = '\\x5c[\\x00-\\x7f]'
  domain_literal = "\\x5b(?:#{dtext}|#{quoted_pair})*\\x5d"
  quoted_string = "\\x22(?:#{qtext}|#{quoted_pair})*\\x22"
  domain_ref = atom
  sub_domain = "(?:#{domain_ref}|#{domain_literal})"
  word = "(?:#{atom}|#{quoted_string})"
  domain = "#{sub_domain}(?:\\x2e#{sub_domain})*"
  local_part = "#{word}(?:\\x2e#{word})*"
  addr_spec = "#{local_part}\\x40#{domain}"
  pattern = /\A#{addr_spec}\z/
end